BEGIN:VCALENDAR VERSION:2.0 PRODID:-//CERN//INDICO//EN BEGIN:VEVENT SUMMARY:The Aharonov-Bohm effect and conic singularities for the Dirac equ ation DTSTART;VALUE=DATE-TIME:20191223T160500Z DTEND;VALUE=DATE-TIME:20191223T161000Z DTSTAMP;VALUE=DATE-TIME:20260419T004915Z UID:indico-contribution-25-154@indico.bitp.kiev.ua DESCRIPTION:Speakers: Eduard Naichuk (Taras Shevchenko National University of Kyiv )\nThe solution of the problem of fermions scattering in one Ahar onov-Bohm vortex involves constructing a one-parameter family of self-adjo int extensions. The Green function can be constructed from the correspondi ng solutions. The following is a comparison of quantum-mechanical scatteri ng problem with quantum field theory problem on the search for correlation functions of fermion states. Namely\, Green's function can be interpreted as correlation function in the space of fermion states. Also there is con sidered a similar problem about scattering of fermions on a conical singul arity\, which implies a similar analysis of the results.\n\nhttps://indico .bitp.kiev.ua/event/4/contributions/154/ LOCATION:Bogolyubov Institute for Theoretical Physics of the National Acad emy of Sciences of Ukraine 322 URL:https://indico.bitp.kiev.ua/event/4/contributions/154/ END:VEVENT BEGIN:VEVENT SUMMARY:Spontaneous and engineered transformations of topological structur es in nonlinear media with gain and loss DTSTART;VALUE=DATE-TIME:20191223T155000Z DTEND;VALUE=DATE-TIME:20191223T155500Z DTSTAMP;VALUE=DATE-TIME:20260419T004915Z UID:indico-contribution-25-116@indico.bitp.kiev.ua DESCRIPTION:Speakers: Oksana Chelpanova (Taras Shevchenko National Univers ity of Kyiv)\nIn contrast to conservative systems\, in nonlinear media wit h gain and loss the dynamics of localized topological structures exhibit m any unique features that can be controlled externally. We propose a robust mechanism to perform topological transformations changing characteristics of dissipative vortices and their complexes in a controllable way. We sh ow that a properly chosen control carries out the evolution of dissipative structures to regime with spontaneous transformation of the topological e xcitations or drives generation of vortices with control over the topologi cal charge.\n\nhttps://indico.bitp.kiev.ua/event/4/contributions/116/ LOCATION:Bogolyubov Institute for Theoretical Physics of the National Acad emy of Sciences of Ukraine 322 URL:https://indico.bitp.kiev.ua/event/4/contributions/116/ END:VEVENT BEGIN:VEVENT SUMMARY:New bounds on axion-like particles from NuSTAR observations DTSTART;VALUE=DATE-TIME:20191223T161000Z DTEND;VALUE=DATE-TIME:20191223T161500Z DTSTAMP;VALUE=DATE-TIME:20260419T004915Z UID:indico-contribution-25-126@indico.bitp.kiev.ua DESCRIPTION:Speakers: Denys Savchenko (Bogolyubov Institute for Theoretica l Physics of the National Academy of Sciences of Ukraine\, Kyiv)\nAxions a re hypothetical particles beyond the Standard Model. Their existence is po stulated to resolve the strong CP problem in QCD. The existence of the axi on-like particles should modify the visible spectra of the cosmic objects due to their coupling to photons in the presence of a magnetic field\, for example\, inside galaxy clusters. For this reason\, they were proposed as one of the explanations for the inconsistencies between Hitomi and Chandr a observations of the 3.5 keV line in Perseus cluster. Furthermore\, axion -like particles could constitute the cold dark matter itself.\nIn this tal k\, we present the upper bounds on the axion-photon coupling from non-dete ction of imprints of such coupling in the NuSTAR observations of the NGC12 75 galaxy\, embedded in the Perseus galaxy cluster.\n\nhttps://indico.bitp .kiev.ua/event/4/contributions/126/ LOCATION:Bogolyubov Institute for Theoretical Physics of the National Acad emy of Sciences of Ukraine 322 URL:https://indico.bitp.kiev.ua/event/4/contributions/126/ END:VEVENT BEGIN:VEVENT SUMMARY:Mathieu equation as a confluent Heun equation and its applications DTSTART;VALUE=DATE-TIME:20191223T160000Z DTEND;VALUE=DATE-TIME:20191223T160500Z DTSTAMP;VALUE=DATE-TIME:20260419T004915Z UID:indico-contribution-25-158@indico.bitp.kiev.ua DESCRIPTION:Speakers: O.V. Yanchyshen (Kyiv Academic University)\nMathieu equation appears in different fields of physics and usually it's known as Schrodinger equation with cosine as potential but in more general sense it's a certain specification of confluent Heun equation. Heun equation i s a second order ordinary differential equation with rational coefficients \, with four regular singular points. Without loss of generality we can pu t these points in $1\, 0\, t\, \\infty$. In our work we consider Mathieu equation and confluent Heun equations and their connection with classical conformal blocks.\n\nhttps://indico.bitp.kiev.ua/event/4/contributions/15 8/ LOCATION:Bogolyubov Institute for Theoretical Physics of the National Acad emy of Sciences of Ukraine 322 URL:https://indico.bitp.kiev.ua/event/4/contributions/158/ END:VEVENT BEGIN:VEVENT SUMMARY:Symmetry breaking in weak- and strong- coupled ring-shaped superfl ows of Bose--Einstein condensates DTSTART;VALUE=DATE-TIME:20191223T153500Z DTEND;VALUE=DATE-TIME:20191223T154000Z DTSTAMP;VALUE=DATE-TIME:20260419T004915Z UID:indico-contribution-25-122@indico.bitp.kiev.ua DESCRIPTION:Speakers: Artem Oliinyk (Department of Physics\, Taras Shevche nko National University of Kyiv)\nOne of the most remarkable manifestation s of quantum properties of superconductors and superfluids is formation of Josephson vortices (JVs)\, alias fluxons\, in long Josephson junctions.\n In this work\, we studied weak- and strong-coupled systems of two parallel superfluid rings with different angular momenta. Atomic Bose-Einstein con densates loaded in a dual-ring trap (two rings separated by a horizontal p otential barrier) suggest a possibility to consider the tunneling dynamics . \nOur research corresponds with investigation of tunneling influence on dynamics of coupled ring-shaped systems of superflows by numerical simulat ions in framework of weakly dissipative mean-field model.\nIn case of weak -coupling\, symmetry breaking suggests Josephson vortex nucleation between the superflows with different angular momenta in low density area. \nIn c ase of strong-coupling (when the barrier is gradually eliminated)\, we obs erved the following situation: the JVs accumulate more and more energy and there is substantially 3D dynamics of vortices. We describe dynamics of c ounter-rotating superflows with and without axial symmetry breaking. It is demonstrated that the population imbalance between the merging flows and the breaking of the underlying rotational symmetry can drive the double-ri ng system to final states with different angular momenta.\n\nhttps://indic o.bitp.kiev.ua/event/4/contributions/122/ LOCATION:Bogolyubov Institute for Theoretical Physics of the National Acad emy of Sciences of Ukraine 322 URL:https://indico.bitp.kiev.ua/event/4/contributions/122/ END:VEVENT BEGIN:VEVENT SUMMARY:Modelling of Spectral Energy Distribution from Protoplanetary Disk of IRAS 22150+6109 DTSTART;VALUE=DATE-TIME:20191223T161500Z DTEND;VALUE=DATE-TIME:20191223T162000Z DTSTAMP;VALUE=DATE-TIME:20260419T004915Z UID:indico-contribution-25-135@indico.bitp.kiev.ua DESCRIPTION:Speakers: Illia Bilinskyi (Taras Shevchenko National Universit y of Kyiv\, Akademika Hlushkova Ave\, 4\, Kyiv\, Ukraine\, 03022)\nWe pres ent the result of modelling of spectral energy distribution of the infrare d source IRAS 22150+6109. The object emits an excess of radiation in far i nfrared band. It was interpreted to be a young massive pre-main-sequence s tar and the protoplanetary disk on late stage. We use radiative transfer code RADMC-3D for the simulations of spectral energy distribution. The cod e itself implements the Monte-Carlo ray tracing method with spherical grid fragmentation. We performed simulations and obtained best-fit parameters for the model of the protoplanetary disk. The investigation of such objec ts will help to understand protoplanetary disks emission better.\n\nhttps: //indico.bitp.kiev.ua/event/4/contributions/135/ LOCATION:Bogolyubov Institute for Theoretical Physics of the National Acad emy of Sciences of Ukraine 322 URL:https://indico.bitp.kiev.ua/event/4/contributions/135/ END:VEVENT BEGIN:VEVENT SUMMARY:Compessibility excess and structurization of binary granular mixtu re DTSTART;VALUE=DATE-TIME:20191223T153000Z DTEND;VALUE=DATE-TIME:20191223T153500Z DTSTAMP;VALUE=DATE-TIME:20260419T004915Z UID:indico-contribution-25-146@indico.bitp.kiev.ua DESCRIPTION:Speakers: Liudmyla Sidletska (Odesa State Environmental Univer sity)\nWe consider the property of compressibility of the binary granular mixture paying attention to their local structurization. The Kirkwood-Buff theory [1] has been used in order to provide theoretical description of t he free volume and compessibility of model bi-component system [2]. Releva nt characters of compactivity has been expressed in terms of partial prope rties of species. For theoretical modelling of respective reference data w e use either hard sphere model or phenomenological data extracted from the physical measurement [3\,4].\nWe show the existence of the nonmonotonic c haracter of the velocity of compaction (different time-scale kinetics) and polodispersive content of system which pass the compression.\n\n[1]. Kirk wood J.G.\, Buff F.P. The statistical mechanical theory of solutions. I. J. Chem. Phys. 19\, 774 (1951)\; https://doi.org/10.1063/1.1748352\n[2]. G erasymov O.I.\, Somov M.M. Statistical description of excess properties of many-particle binary systems. Ukr. J. Phys. 60\, 324 (2015)\; https://doi .org/10.15407/ujpe60.04.0324\n[3]. Aliotta F.\, et al. Excess compressibil ity in binary liquid mixtures. J. Phys. Chem. 126\, 224508 (2007)\; https: //doi.org/10.1063/1.2745292\n[4]. Pilliteri S.\, Lumay G.\, Opsomer E.\,Va ndewalle N. From jamming to fast compaction dynamics in granular binary m ixtures. Sci. Rep. 9\, 7281 (2019)\; https://doi.org/10.1038/s41598-019-43 519-6\n\nhttps://indico.bitp.kiev.ua/event/4/contributions/146/ LOCATION:Bogolyubov Institute for Theoretical Physics of the National Acad emy of Sciences of Ukraine 322 URL:https://indico.bitp.kiev.ua/event/4/contributions/146/ END:VEVENT BEGIN:VEVENT SUMMARY:Ferroelectric nanocomposites: influence of nanoparticle sizes dist ribution on pyroelectric and electrocaloric conversion parameters DTSTART;VALUE=DATE-TIME:20191223T154500Z DTEND;VALUE=DATE-TIME:20191223T155000Z DTSTAMP;VALUE=DATE-TIME:20260419T004915Z UID:indico-contribution-25-138@indico.bitp.kiev.ua DESCRIPTION:Speakers: Hanna Shevliakova (Department of Microelectronics\, National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”\, Kyiv\, Ukraine)\nPyroelectric (PE) and electrocaloric (EC) properties on the ferroelectric-antiferroelectric phase boundary of ferro electric (FE) thin films\, multilayers and other low-dimensional materials can significantly differ from PE and EC properties of bulk single crystal s\, solid solutions and ceramics. In fact\, even for FE nanoparticles\, fo r which efficient synthesis procedures and methods for controlling polar p roperties have already been developed\, there are still many technological problems [1] and the mysteries of theory [2]. In particular\, under consi deration of EC effect in BaTiO3 nanoparticle within the core–shell model [3]\, the depolarization effects\, which are inevitable in the case of ze ro polarization\, were completely neglected. This fact does not allows to apply the obtained in Ref. [1] results to real systems. Using phenomenolog ical Landau-Ginsburg-Devonshire theory and the approximation of the effect ive medium\, typical dependences of the parameters PE and EC conversion on the external electric field\, temperature\, and radius for spherical mono domain FE nanoparticles with fixed radius were calculated analytically in Ref. [4]. In this work typical dependences of the parameters PE and EC con version for nanocomposites with spherical monodomain FE nanoparticles of d ifferent sizes have been calculated analytically.\n\n[1]. U. Idehenre\, Y. A. Barnakov\, S. A. Basun\, D. R. Evans\, Spectroscopic studies of the ef fects of mechanochemical synthesis on BaTiO3 nanocolloids prepared using h igh-energy ball-milling\, J. Appl. Phys.\, 124\, pp. 165501-1-5\, (2018).\ n[2]. Y. A. Barnakov\, I. U. Idehenre\, S. A. Basun\, T. A. Tyson\, D. R. Evans\, Uncovering the mystery of ferroelectricity in zero dimensional nan oparticles\, Nanoscale Advances\, 1\, pp. 664-670\, (2019).\n[3]. C. Xiqu and C. Fang\, Study of electrocaloric effect in barium titanate nanopartic le with core–shell model\, Physica B: Cond. Matt.\, 415\, pp. 14-17 (201 3).\n[4]. A. N. Morozovska\, E. A. Eliseev\, M. D. Glinchuk\, H. V. Shevli akova\, G. S. Svechnikov\, M. V. Silibin\, A. V. Sysa\, A. D. Yaremkevich\ , N. V. Morozovsky\, and V. V. Shvartsman\,. Analytical description of the size effect on pyroelectric and electrocaloric properties of ferroelectri c nanoparticles\, Phys. Rev. Materials\, Vol. 3\, Iss. 10\, 104414\, (2019 ).\n\nhttps://indico.bitp.kiev.ua/event/4/contributions/138/ LOCATION:Bogolyubov Institute for Theoretical Physics of the National Acad emy of Sciences of Ukraine 322 URL:https://indico.bitp.kiev.ua/event/4/contributions/138/ END:VEVENT BEGIN:VEVENT SUMMARY:The covalent radii derived from the first-principle data DTSTART;VALUE=DATE-TIME:20191223T162000Z DTEND;VALUE=DATE-TIME:20191223T162500Z DTSTAMP;VALUE=DATE-TIME:20260419T004915Z UID:indico-contribution-25-152@indico.bitp.kiev.ua DESCRIPTION:Speakers: Valerii Chuiko (Faculty of Physics of Taras Shevchen ko National University of Kyiv)\nThe concept of atomic covalent radius for ms the basis for one of the simplest parameterizations for prediction of t he covalent bond length and recovering molecular graphs from the set of in teratomic distances. In the present contribution we adopt the recently pro posed dataset [1] of covalent bond lengths resulting from the first-princi ple calculations to derive the covalent radii for H\, B\, C\, N\, O\, F\, Si\, P\, S\, Cl\, Ge\, As\, Se and Br elements within the additive covalen t bond length model. The obtained first-principle covalent radii are shown to be in good agreements ones based on empirical data [2]. Availability o f the large-size dataset of covalent bond lengths enabled the further anal ysis of errors in approximating the covalent bond length with the sum of t he covalent radii. In particular\, the effects of electronic conjugation a nd the chemical elements electronegativity difference were investigated [3 ].\n\n[1] Nikolaienko\, T. Y.\, Chuiko\, V. S.\, & Bulavin\, L. A. (2019). The dataset of covalent bond lengths resulting from the first-principle c alculations. Computational and Theoretical Chemistry\, 112508.\n[2] Pyykk ö\, P. (2015). Additive covalent radii for single-\, double-\, and triple -bonded molecules and tetrahedrally bonded crystals: a summary. The Journa l of Physical Chemistry A\, 119(11)\, 2326-2337.\n[3] Nikolaienko\, T. Y.\ , Chuiko\, V. S.\, & Bulavin\, L. A. (2019). The covalent radii derived fr om the first-principle data. arXiv preprint arXiv:1906.11724\n\nhttps://in dico.bitp.kiev.ua/event/4/contributions/152/ LOCATION:Bogolyubov Institute for Theoretical Physics of the National Acad emy of Sciences of Ukraine 322 URL:https://indico.bitp.kiev.ua/event/4/contributions/152/ END:VEVENT BEGIN:VEVENT SUMMARY:Binding of antibiotic drug molecules to the surface of silver nano particles: tight-binding DFT study DTSTART;VALUE=DATE-TIME:20191223T162500Z DTEND;VALUE=DATE-TIME:20191223T163000Z DTSTAMP;VALUE=DATE-TIME:20260419T004915Z UID:indico-contribution-25-153@indico.bitp.kiev.ua DESCRIPTION:Speakers: Olha Husak (Faculty of Physics of Taras Shevchenko N ational University of Kyiv)\nEnhancement of therapeutic activity of organi c drug molecules bound to nanoparticle surface has recently been highlight ed as a possible way to overcome resistance of bacteria towards traditiona l antibiotics [1]. Investigation of the physical interactions responsible for such complexation\, however\, becomes challenging when nanoparticle is formed by transition metal atoms due to the need of accurate treatment of the nanoparticle polarizability [2]. Purely ab initio approaches\, on the other hand\, are typically ruled out by the number of atoms in such syste ms and consequent demands for computational resources. In the variety of m olecular modeling approaches available nowadays\, the density-functional b ased tight-binding (DFTB) method is unique in combining the clear hierarch y of physically sound approximations with high computational efficiency [3 ]\, thus\, being ideal for treating the systems of hundreds of atoms in re asonable time.\nIn the present contribution we report the applications of DFTB-based automated conformational searching algorithms [4] to obtain the energetically most stable complexes formed by organic drug molecules Ceft riaxone and Doxorubicin with silver nanoparticles (ca. 1 nm diameter) of d ifferent shapes. \n\n[1] A. Panáček\, M et al.\, Molecules (2016)\, Vol. 21\, P. 26.\n[2] F. Iori\, S. Corni. J. Comput. Chem.(2008)\, 29(10)\, 1 656-1666.\n[3] J. Cuny\, N. Tarrat\, F. Spiegelman\, A. Huguenot\, M. Rap acioli. J. Phys. Condens. Matter (2018)\, Vol. 30\, p. 303001.\n[4] S. Gri mme. ‎J. Chem. Theory Comput (2019)\, 15(5)\, 2847-2862.\n\nhttps://indi co.bitp.kiev.ua/event/4/contributions/153/ LOCATION:Bogolyubov Institute for Theoretical Physics of the National Acad emy of Sciences of Ukraine 322 URL:https://indico.bitp.kiev.ua/event/4/contributions/153/ END:VEVENT BEGIN:VEVENT SUMMARY:Determination of the contact angle from transversality conditions of the Lagrange variation problem of wetting DTSTART;VALUE=DATE-TIME:20191223T155500Z DTEND;VALUE=DATE-TIME:20191223T160000Z DTSTAMP;VALUE=DATE-TIME:20260419T004915Z UID:indico-contribution-25-156@indico.bitp.kiev.ua DESCRIPTION:Speakers: Oleh Hrebnov (Taras Shevchenko National University o f Kyiv)\nIn recent years\, there has been an increase in studies focused o n the size-dependent contact angle. In the case of the sessile axial symme tric droplet\, the size dependence often is explained by the contribution of the line tension to the Helmholtz free energy as a consequence\, the mo dified Young's equation. There are two major points of view on the contrib ution mechanism. According to the first point of view\, the liner tension is a function of the contact angle\; according to another one\, the line t ension is a function of the three-phase contact line torsion and geodesic curvature. However\, in the case of the straight contact line\, it is impo ssible to determine the influence of the line tension of the three-phase c ontact line on the contact angle. \nWe propose a model of the line tension of the three-phase contact line influence on the contact angle. We consid er the line tension as a thermodynamic work on the deformation transition region on the three-phase border to determine the influence. Therefore\, t he line tension becomes a function of the dividing surface curvature on th e contact line. Then\, the Helmholtz free energy of a unit of the cylindri c nanodroplet length $\\Delta\\textit{x}$ with the additional condition of incompressibility of the nanodroplet liquid is:\n$$\n\\begin{multline}\n\ \ F\\left[z\\left(y\\right)\\right]=\\int\\limits_{x}^{x+\\Delta x}dx \\in t\\limits_{-r}^{r}dyL\\left(y\,z\,z'\,z''\\right)= \\\\\n \\int\\limits_{x }^{x+\\Delta x}dx \\int\\limits_{-r}^{r}dy\\left\\{\\gamma _{sv }-\\gamma _{sl} +\\gamma _{lv } \\left[\\frac{z''^{2} }{\\left(1+z'^{2} \\right)^{3/ 2} } \\right]\\sqrt{1+z'^{2} } +\\frac{1}{r} \\tau \\left[\\frac{z''^{2} } {\\left(1+z'^{2} \\right)^{3/2} } \\right]+\\lambda yz'\\right\\}\,\n\\end {multline}\n$$\nwhere\, $\\textit{2r}$ $-$ the width of the nanodroplet b ase\, $\\gamma$ $-$ the surface tension between liquid/vapor\, solid/liqui d and solid/vapor\, $\\tau$ $-$ the line tension of three-phase contact li ne\, $\\lambda$ $-$ Lagrange multiplier.\nThe transversality conditions of the Lagrange problem with moving boundary for the functional containing t he second-order derivative are:\n$$\n\\begin{equation}\n{\\left[L-z'\\left (\\frac{\\partial L}{\\partial z'}-\\frac{d}{dy} \\frac{\\partial L}{\\par tial z''} \\right)+\\right. \\left. \\left(\\frac{z'\\arctan \\left(z'\\ri ght)\\left(1+z'^{2} \\right)-z'^{2} }{y\\left(\\arctan \\left(z'\\right)-z '\\right)} -z''\\right)\\frac{\\partial L}{\\partial z''} \\right]_{y=-r\, r}=0 }.\n\\end{equation}\n$$\nThe contact angle can be obtained by minimiz ation of the Helmholtz free energy functional with the application of the transversality conditions:\n$$\n\\begin{equation}\n\\left(1-\\left(\\frac{ \\delta _{c} }{R} \\right)+o \\left(\\frac{\\delta _{c} }{R} \\right)^{2} \\right)\\cos \\left(\\theta \\right)=\\frac{\\gamma _{sv } -\\gamma _{sl} }{\\gamma^{\\infty } {}_{lv} } -\\frac{\\tau}{\\gamma^{\\infty } {}_{lv} R\\sin \\left(\\theta \\right)}\,\n\\end{equation}\n$$\nwhere\, $\\delta{} _{c}$ $-$ the Tolman length\, $\\theta$ $-$ the contact angle\, $\\gamma$$ {}^{\\mathrm{\\infty}}{}_{lv}$ $-$ the surface tension of a flat surface\, $R$ $-$ the radius of the liquid-vapor interface curvature.\nIt has been shown that the contact angle depends on the line tension of the straight t hree-phase contact line.\n\nhttps://indico.bitp.kiev.ua/event/4/contributi ons/156/ LOCATION:Bogolyubov Institute for Theoretical Physics of the National Acad emy of Sciences of Ukraine 322 URL:https://indico.bitp.kiev.ua/event/4/contributions/156/ END:VEVENT BEGIN:VEVENT SUMMARY:DNN application for hydrodynamic task solution DTSTART;VALUE=DATE-TIME:20191223T163000Z DTEND;VALUE=DATE-TIME:20191223T163500Z DTSTAMP;VALUE=DATE-TIME:20260419T004915Z UID:indico-contribution-25-155@indico.bitp.kiev.ua DESCRIPTION:Speakers: Kirill Taradiy (Frankfurt Institute for Advanced Stu dies\, Frankfurt am Main\, Germany)\nThe possibility of GPU usage combined with the substitution of numerical computations with the trained neural n etwork for both relativistic and non-relativistic hydrodynamic equations y ields the 104 - 106 performance boost compared to the standard numerical m ethods. The main idea behind the work starts from the fact that neural net work is the so-called perceptron on the universal type. The deep sense beh ind this definition is that actually a neural network with one hidden laye r can become the mapping of any type for smooth differentiable continuous functions. The trained Neural Network can as well perform the role of the time-dependent solution of the hydro-equations performing the regression a nd classification tasks for various types of hydro – solutions. The resu lts of DNN application to the non-relativistic hydro problem are demonstra ted for 1D and 2D cases. Further 3D generalization options and problems ar e discussed.\n\nhttps://indico.bitp.kiev.ua/event/4/contributions/155/ LOCATION:Bogolyubov Institute for Theoretical Physics of the National Acad emy of Sciences of Ukraine 322 URL:https://indico.bitp.kiev.ua/event/4/contributions/155/ END:VEVENT BEGIN:VEVENT SUMMARY:Analogue Hawking radiation in a ring of Bose-Einstein condensate DTSTART;VALUE=DATE-TIME:20191223T154000Z DTEND;VALUE=DATE-TIME:20191223T154500Z DTSTAMP;VALUE=DATE-TIME:20260419T004915Z UID:indico-contribution-25-143@indico.bitp.kiev.ua DESCRIPTION:Speakers: Igor Yatsuta (Department of Physics\, Taras Shevchen ko National University of Kyiv)\nHawking radiation is one of the most fasc inating phenomena taking place near the black hole horizon. Featuring both gravitational and quantum properties this effect is extremely hard to obs erve on the real objects. Surprisingly\, it is possible to mimic evaporati on of particles on the acoustic analogs\, where Bose-Einstein condensate p lays a role of background giving birth for Hawking pairs. This area is sti ll a matter of multiple discoveries providing us with the very first convi ncing observation of Hawking effect analog this year.\n$~~~~~~~~$We addres s a model of effectively one-dimensional (1D) Bose-Einstein condensate (BE C) confined in a toroidal trap. This system is attractive to explore since the total flow of quantum liquid is quantized which results in a restrict ion on possible values of the velocity of the condensate. Moreover\, it is impossible to avoid the presence of the so-called white hole (inner) hori zon in such toroidal geometry.\n$~~~~~~~~$Unlike recent works on the acous tic horizon in toroidal BECs\, we apply the method previously used for mod eling an infinitely long quasi-one-dimensional condensate to our system. I t allows to create acoustic horizons in the condensate with uniform densit y. Remarkably\, we managed to see the correlation pattern having the prope rties of the analog Hawking effect. Obtained correlations turned out to be strongly dependent on the length of the ring and initial noise for the fi xed parameters of the horizon. Furthermore\, for some particular size of the region Hawking correlations disappear that may be an interesting analo gy of the existence of Planck mass limit for real black holes. Also\, we c onsidered the influence of the white hole horizon on the correlation patte rn and stability of the system for different values of surface gravity.\n\ nhttps://indico.bitp.kiev.ua/event/4/contributions/143/ LOCATION:Bogolyubov Institute for Theoretical Physics of the National Acad emy of Sciences of Ukraine 322 URL:https://indico.bitp.kiev.ua/event/4/contributions/143/ END:VEVENT BEGIN:VEVENT SUMMARY:Effects of parallel motion on test-particle transport DTSTART;VALUE=DATE-TIME:20191223T163500Z DTEND;VALUE=DATE-TIME:20191223T164000Z DTSTAMP;VALUE=DATE-TIME:20260419T004915Z UID:indico-contribution-25-163@indico.bitp.kiev.ua DESCRIPTION:Speakers: O.M. Cherniak (Bogolyubov Institute for Theoretical Physics of the Natioanal Academy of Sciences of Ukraine\, Kyiv)\nTransport processes play a significant role in the evolution of non-equilibrium pla smas. Various instabilities which exist in such plasma can generate intens e fields that interact with particles and cause the anomalous transport. T he intensity of the generated fields can be high enough to cause anomalous transport exceeding the collisional one. The possible explanation of a si gnificant difference between anomalous and collisional transport character istics is the particle trapping effect.\n The particle trapping effect is the crucial feature for a two-dimensional transport across the magnetic fi eld\, particularly when random electric field has an infinite correlation time. One of the common methods for a theoretical study of this problem is based on the Taylor relation combined with a certain statistical approxim ation of velocity correlation function along the trajectories. In our prev ious work we proposed and validated closure approximation [1] for an infin ite correlation time and expanded it to account for finite Larmor radius e ffects [2] as well as finite correlation time [3]. However\, it is also im portant to study the effect of the particle motion along the magnetic fiel d on the particle transport. \n Here we use numerical simulation to study three-dimensional particle motion in constant magnetic and random electric fields. A set of parameters\, such as random field correlation time\, fin ite Larmor radius and initial longitudinal velocity are considered. The ef fect of these parameters on particle transport are discussed.\n This work is supported by the Project № 20-04/18-2019 of the National Academy of Sciences of Ukraine.\n\n[1] V.I. Zasenko\, A.G. Zagorodny\, O.M. Chernyak\ , Ukr. J. Phys. 56\, 1007 (2011).\n[2] O.M. Cherniak\, V.I. Zasenko\, Ukr. J. Phys. 62\, 495 (2017).\n[3] O.M. Cherniak\, V.I. Zasenko\, J. Phys. Co nf. Ser. 1197\, 012003 (2019).\n\nhttps://indico.bitp.kiev.ua/event/4/cont ributions/163/ LOCATION:Bogolyubov Institute for Theoretical Physics of the National Acad emy of Sciences of Ukraine 322 URL:https://indico.bitp.kiev.ua/event/4/contributions/163/ END:VEVENT END:VCALENDAR